Modelling of Buoyancy Driven Flows along a Building Wall in an Urban Environment

Abstract

This paper discusses the modelling of buoyancy driven flows along building walls using analytical and Computational Fluid Dynamics (CFD) models. Two separate models to estimate the temperature distribution along a vertical building wall have been developed. One of the models was developed using regression analysis of field measurements carried out in France, and the other being a modified version of the integral momentum equation used for natural convection flows for a vertical flat plate. In addition, CFD modelling of buoyancy driven flows along a building wall using the standard k-e model has also been presented. Results show that both the models provide good comparisons with previous experimental data (root mean square error < 0.2), and hence can be used to predict the temperature distribution along a building wall. CFD simulations of natural convection flows along the wall provide excellent insight into the airflow process and temperature distributions. The analytical models can be utilised by engineers and architects for designing a city in order to improve the air quality and provide better thermal comfort. Design guidelines for improved air flow conditions and better thermal comfort in a city are also provided. It is expected that in future, CFD will be used extensively for such studies, although the simulations must always be validated with field measurements.